Materials called metamaterials make possible a prism that may someday lead to major disappearing acts. Also, how some people can be both fat and healthy. Transcript of radio broadcast:

VOICE
ONE:

This is
SCIENCE IN THE NEWS in VOA Special English.
I'm Bob Doughty.

VOICE
TWO:

And
I'm Barbara Klein. This week, we will
tell about evidence that some people can be both fat and healthy. We will also tell about brain aneurysms -- a
rare but deadly disorder. And, we will
tell about materials that could help make objects seem to disappear.

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VOICE
ONE:

Two
studies are suggesting that some overweight people do not always face an
increased risk of developing heart disease. Researchers also found that some normal body weight individuals have an
increased risk of the disease.

Being
overweight does increase your risk of medical problems. But the studies found that not all heavy
people are less healthy than thin people.

VOICE
TWO:

In one
study, American researchers examined medical records from more than five
thousand men and women. Each person had
taken part in a separate study from nineteen ninety-nine to two thousand
four.

The researchers found that about
fifty-one percent of the subjects were overweight or obese. About thirty-two percent were obese, but
considered metabolically healthy. This
means they had no evidence of problems in tests for high blood pressure or
other measures linked to heart disease.

However,
more than twenty-three percent of people who were at a healthy weight had two
or more unhealthy measurements in the tests.

VOICE
ONE:

Judith Wylie-Rosett helped supervise the
American study. She is a professor at
the Albert Einstein College of Medicine at Yeshiva University in New York. Professor Wylie-Rosett says the findings
show that an obese person can still be healthy. She believes that having body fat is not as important to health
as where the fat is found on body.

America's
Centers for Disease Control and Prevention notes that two-thirds of Americans
are considered overweight or obese.

VOICE
TWO:

A second study is suggesting that fat in
the liver may be important to health risks.
Norbert Stefan and his team work at Germany's University of
Tubingen. They closely examined three
hundred fourteen people. They measured
how much body fat each person had, and where it was on the body. To do this, they used medical imaging
tests. They too discovered that obese
people could have healthy hearts. Their
results suggest that fat in the liver is more dangerous than fat in other
areas.

The
results of both studies were published recently in the Archives of Internal
Medicine.

VOICE
ONE:

Professor
Wylie-Rosett says the findings do not mean that people should not be concerned
about becoming obese. Experts say there
are several diseases linked to obesity that make it more dangerous to be fat
than thin. They say that people should
see their doctor to learn what health risks they may be facing and what
behaviors should be changed to improve health.

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VOICE
TWO:

We
often hear the term brain aneurysm.
Joseph Biden had two brain aneurysms twenty years ago. Doctors saved his life. Recently, the senator from Delaware was
named the vice presidential choice of the Democratic Party.

Ohio's
first black congresswoman was not so lucky, however. Representative Stephanie Tubbs Jones died last month within hours
after a brain aneurysm burst. Doctors
said she may have had no warning.

VOICE
ONE:

A brain aneurysm is a weak or thin area
along an artery wall in the brain. It
can become so thin that it ruptures and bleeds.

The
most common form looks like a small, round berry hanging from the artery. The Mayo Clinic in Minnesota says as many as
fifteen million people in the United States, or five percent, have a berry
aneurysm. Fewer than thirty thousand
will ever suffer a rupture.

The
National Institute of Neurological Disorders and Stroke says forty percent of
victims die within twenty-four hours.
Another twenty-five percent die within six months.

VOICE
TWO:

People
may live a long and healthy life and never know they have an aneurysm. But sometimes, if it gets big enough, it can
cause pain or other problems that lead to its discovery.

In Senator Biden's case, his neck hurt
for several weeks. Doctors thought he
had a pinched nerve and a virus. But in
February of nineteen eighty-eight, tests showed a leaking artery at the base of
his brain. Doctors operated
successfully, and again three months later for an aneurysm in another area.

Experts
say most brain aneurysms happen in people born with an abnormality in an artery
wall. Other causes can include head
injuries, high blood pressure, infections, tobacco use and use of stimulant
drugs.

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VOICE
ONE:

For years, scientists have dreamed of
someday guiding or directing light in unusual ways. If they could, objects might seem to disappear. The objects would be invisible -- hidden
from sight.

Now,
scientists in the United States have produced materials that may help to make
invisibility possible. Researchers at
the University of California in Berkeley performed the experiments. Their study took steps toward "cloaking", or
appearing to hide, objects.

The
Lawrence Berkeley National Laboratory also took part in the experiments. Support for the work came from America's
National Science Foundation and the United States military.

VOICE
TWO:

Before
now, invisibility experiments succeeded in guiding light around only very thin
objects of two dimensions. Such objects
had length and width, but no depth. The
new study marks the first time experiments have been successfully done in three
dimensions using visible light, or light that can be seen.

We normally see objects because light
strikes them. Then our eyes receive
some of the light from the objects. To
make an object seem to disappear, it is necessary to direct the light so it
hides the object.

The
California researchers successfully did this by using materials called
metamaterials. Metamaterials are small
almost beyond human imagination. They
are made with a process called nanoengineering.

VOICE
ONE:

It was
thought that directing light with natural materials was not possible. But with nanoengineered materials, the
researchers were able to build a special prism. Normally, a prism has many flat surfaces. It divides white light into colors. A nanoengineered prism does the
opposite. It creates white light from
colors.

Results
of the experiment were reported in "Science" magazine. Results with the other metamaterial appeared
in the publication "Nature." University
of California Professor Xiang Xhang led the research teams that developed both
materials. They contained substances
including metals, earthenware and fiber.

VOICE
TWO:

The
researchers designed one metamaterial like a net used to trap fish. It was made of silver nanowires. Each wire was about ten thousand times
thinner than a human hair. The other
metamaterial used twenty-one grids of silver and magnesium fluoride. The box-like grids formed lines. They were also unimaginably small.

Two years ago, two other researchers
also reported on invisibility experiments.
But they used microwaves instead of visible light. The two men were David Smith of Duke University
in the United States and John Pendry of Imperial College in London.

Last year, scientists at America's
Purdue University reported success in guiding light around objects placed in a
design. The design employs small
needles called – you guessed it – nanoneedles.
Mister Pendry, Mister Smith and David Schurig developed some of the
required mathematics for that research.
At the same time, so did Ulf Leonhardt of the University of Saint
Andrews in Scotland.

VOICE
ONE:

All
this recent interest in invisibility is not surprising. People have been talking about making things
invisible for thousands of years. In
Plato's "Republic", there is an invisible ring. In the last century, "The Shadow" was a popular radio program. It told of a man who could become
invisible. That meant he could defeat
all evil.

More recently, the British secret agent
of many films, James Bond, had an invisible car. And Harry Potter, hero of many books and films, sometimes had a
magic cloak. He was able to protect
himself by wearing it.

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VOICE
TWO:

This
SCIENCE IN THE NEWS program was written by Jerilyn Watson, Caty Weaver and
Brianna Blake, who also was our producer.
I'm Barbara Klein.

VOICE
ONE:

And
I'm Bob Doughty. We would like to hear
from you. You can read and
listen to our programs at voaspecialenglish.com. Join us
again next week for more news about science in Special English on
the Voice of America.